The present invention relates to a ball screw assembly of the type in which a nut having an internal helical groove is telescoped over an elongated shaft having an opposing helical groove and an endless train of balls is disposed in the grooves so that the nut travels axially along the shaft as the latter is turned relative to the nut. The invention is particularly concerned with an assembly which utilizes a stop acting between the shaft and the nut to limit the travel of the nut to a position in which the stop is engaged. In some applications, the kinetic energy of the nut and any parts it may carry is of such a magnitude that the force of impact against the stop may be great enough to have a detrimental effect.